Strength Analysis And Lightweight Design Of Marine Diesel Engine Block Based On Multi Component Coupling

With the improvement of diesel engine power density and enhancement indicators,modern diesel engines require both higher output power and lower overall weight.The engine block is one of the components that account for the largest proportion of internal weight of a diesel engine.The lightweight design of the engine block will effectively reduce the overall weight of the diesel engine.With the development of computer technology,using finite element method to calculate the stress and strain of components has become the mainstream.Lightweight design of structures based on stress calculation data is an important means of modern diesel engine design.This paper takes a marine inline six cylinder diesel engine as the research object,calculates the stress changes of the diesel engine body and other moving parts,and uses the stress calculation data of the body as the input for fatigue analysis.It calculates the fatigue characteristics of the body,points out the defects in the original diesel engine body design,and completes the optimization design of the body.Traditional body strength analysis usually only focuses on the stress of the cylinder body under explosive conditions,ignoring the inertial force of moving components and the impact of direct contact between different components.With the improvement of modern diesel engine strengthening indicators,more accurate stress calculations are urgently needed to verify the body strength and provide a reference for body fatigue and lightweight.In this paper,a transient dynamic analysis based on multi component coupling is used to analyze the stress changes of the computer body during two working cycles(1440 ° CA),taking into account the impact of inertia forces of moving components such as crankshaft,connecting rod,and piston on the stress of the body.At the same time,the precision of nonlinear contact calculation in finite element calculation is optimized by refining the contact area.In order to ensure the accuracy of stress calculation,this article has carried out cylinder pressure measurement tests and body stress measurement tests.The test results prove that the error of body stress calculation is within 5%,providing accurate data reference for fatigue analysis of the body.The traditional lightweight design of the body is usually limited to removing redundant materials from local areas,generally without changing the overall structure of the body,and the lightweight effect is very limited.This paper studies the effects of design parameters such as body material and wall thickness on the stress of the body,finds the optimal design parameters for the body,and adjusts the body structure based on stress and fatigue calculation data.This not only reduces the weight of the body,but also optimizes the overall structure of the body.The research simulation results show that the maximum stress of the engine body studied in this paper is 160.42 MPa,and the area with large stress is located at the bolt connection between the cylinder head and the engine body.There is stress concentration in the area with sharp angles in the engine body,but the maximum stress is less than the yield limit of the engine body material of 450 MPa,which meets the static strength requirements;The service life of the engine body is 4.627 million hours,meeting the design requirements for infinite life.There is fatigue damage at the main bearing seat and connecting bolt positions.The lightweight design results of the body show that the thickness of the body wall and the height of the diaphragm stiffeners have a significant impact on the maximum stress of the body.After the lightweight design,the overall weight of the body has decreased by 14.8%,and the power density has increased by 17.4%.The maximum stress and life of the lightweight body meet the design requirements.This paper solves the problem of insufficient accuracy in traditional static calculation in the field of diesel engine block strength calculation,proposes a joint analysis method based on multi component coupling transient dynamic strength analysis and fatigue life calculation for the block,studies the impact of block design parameters on the block strength,realizes the lightweight design of the block,and provides a method reference for the strength analysis and lightweight design of diesel engine blocks.